1. Field of the Invention
The invention relates to a process for recycling bulk rubber and polymeric materials. More particularly, it relates to a tire recycling process.
When polymers, and rubber material are disposed as garbage, there is a great waste in material that can be recycled. In order to convert this waste material into valuable products, it must be reduced in size and then recycled. This invention relates to an environmentally safe process for reducing this waste product to a usable material to facilitate the future recycling.
2. The Prior Art
The patent to Enikopolov et al, U.S. Pat. No. 4,607,796, discloses a method of making powder from rubber and vulcanization products. This inventive process includes compression to allow for greater pulverization. The material is then cooled to a temperature in a range of 15.degree. C. to 60.degree. C. under pressure and shear conditions. In addition, the pulverization process can be done in the presence of a polyethylene additive to improve the degree of comminution.
The patent to Rouse et al., U.S. Pat. No. 5,238,194, discloses a method of producing fine elastomeric or rubber particles. This process involves the following steps: First, establishing an excessive flow of water through an open set of non-rotating grinding stones. Second, the stones are rotated at full speed until a desired pressure of closure is achieved. Then the grinding mill is fed with a slurry of carrier liquid and the material is then ground while closing the water flow used to establish the flow rate. The energy expended in rotating the grinding stones is dissipated into the slurry as heat.
The patent to Rutherford Sr., U.S. Pat. No. 5,115,983, discloses a process for recycling vehicle tires. The process consists of shredding the rubber from a tire while separating the shredded rubber from the cording and beading material of the tire. This process is performed by placing the tire in a chamber and subjecting the tire to high pressure water jets. Water fired from the water jets hits the tire at a pressure of at least 2000 psi not to exceed 10,000 psi. By exposing the tire to the pressurized water streams for a predetermined period of time, the rubber is shredded from the tire and the cording and beading are also separated therefrom.
U.S. Pat. No. 4,726,530 to Miller et al., discloses a method of resource recovery from used tires. This process involves shredding tires into small pieces, screening the shredded pieces, re-shredding and re-screening the pieces. Then, the pieces of tires are granulated to the desired size. Finally, the material is separated through the use of an air separator and a magnetic separator.
The patent to Morris, U.S. Pat. No. 5,024,386 discloses a tire converting apparatus and method. This method starts by debeading the tire, and cutting the tire into two segments. The sidewalls of the cut segment are spread apart and then the segment is held flat, finally the flat segment is fed into a shredder and the shredded pieces are then recovered for further use.
The Patent to Brubaker et al, U.S. Pat. No. 4,625,922 discloses an elevated temperature comminution of vulcanized rubber and other elastomers. The invention consists of reducing the viscosity of the slurry before it is fed into the commuting zone. This involves heating the pellets into a slurry at 130.degree. F. by either vibration or hot water.
There are disadvantages to the prior art. The process of grinding the tires has not proved sufficient. In order to reduce the tires or other recyclable materials to a fine powder, the rubber material must be reduced to a brittle state. The prior art uses either inadequate temperatures for milling, or costly cooling methods that utilize liquid nitrogen or other cryogenic chemicals in order to achieve the required cryogenic temperatures.